Furstrated- Unable to get rated solar Amperage

[Sunking]

At the very best a PWM is 66% efficient. MPPT up around 95%.

[mapmaker]

oh my! you mean pwm is only 55 percent efficient? and how efficient I'd Mppt then?

A PWM controller can be much more efficient, or much less efficient than 55%. It depends on the overall system design.

Same holds for MPPT. I could design a system where the PWM would be more efficient than the MPPT.

--mapmaker

[bhvm]

That would be correct for PWM.

oh my! you mean pwm is only 55 percent efficient? and how efficient I'd Mppt then?

wish I had come to this site before. could have saved a lot of headache!

[Sunking]

Sorry for the delayed update. I had a heated talk with the Dealer and He is finally giving me MPPT. He already tried various PWM and max i got was 550W out of a 1000W worth of 4 Panels.

That would be correct for PWM.

[bhvm]

Yes, you can use 2 controllers on the same battery. Each controller will need its own array... that means each array will need its own cable to its own controller.

I know nothing about the quality of the controllers you mention, but given that your installer has proven himself to be unqualified, why do you trust him to sell you a controller that he has never used or installed?

--mapmaker

I understand your concerns,map maker.
as I have paid advance cash for lump sum project to him, I will be for a loss if I leave him. that's why it's mandatory to get the project done from said person.

that aside ,reading the pdf spec and manual makes me feel that these are absolute high end controllers one can have in India. actually it's me who found these controllers but he will be buying them on my behalf.
I will report back once they land up here. thanks

[mapmaker]

Problem is, the model is rated only upto 20A. 40A model is not available.
Is it okay to use two MPPT in parallel to generate 40A for batteries? (By putting 2 panels per controller)

Yes, you can use 2 controllers on the same battery. Each controller will need its own array... that means each array will need its own cable to its own controller.

I know nothing about the quality of the controllers you mention, but given that your installer has proven himself to be unqualified, why do you trust him to sell you a controller that he has never used or installed?

--mapmaker

[bhvm]

Sorry for the delayed update. I had a heated talk with the Dealer and He is finally giving me MPPT. He already tried various PWM and max i got was 550W out of a 1000W worth of 4 Panels.

The MPPT he's giving me is-

http://www.systellar.in/solar-power-backup-system.html

http://www.systellar.in/public_html/systellar.in/userfiles/files/Charge%20controller/MPPT/MPPT%20CC%20-%20Technical%20specs%20Apr%202014.pdf

http://www.systellar.in/public_html/systellar.in/userfiles/files/Charge%20controller/MPPT/User%20Manual%20MPPT%20Charge%20controller.pdf

Problem is, the model is rated only upto 20A. 40A model is not available.
Is it okay to use two MPPT in parallel to generate 40A for batteries? (By putting 2 panels per controller)

However this MPPT is on Non-refundable basis, so if I get less output, damage is mine. What ya say folks? Jump the gun?

[Sunking]

Hello again
I had the tech visit again.
They checked the controllers are found them fine. Now they are thinking to replace the Panels.
Perhaps they'll give me 42v ones like you suggested.

However I have insisted that i'd like to try MPPT before swapping anything. Lets see how it goes.

Your so called tech is dumber than a rock. A single good quality MPPT controller is a lot less expensive then new panels.

[bhvm]

Hello again
I had the tech visit again.
They checked the controllers are found them fine. Now they are thinking to replace the Panels.
Perhaps they'll give me 42v ones like you suggested.

However I have insisted that i'd like to try MPPT before swapping anything. Lets see how it goes.

[bhvm]

Thanks for bringing to notice. There are clouds and storms these days. So my project is on hold till skies clear.

[mapmaker]

What shall be a better panel voltage to charge 24v system via PWM? If so I could ask him to change the type of panels.

Sunking answered that question in the very first reply to this thread. You need Vmp = 36 volts. The Voc of such a panel will be about 44 volts.

--mapmaker

[bhvm]

I can only guess the technician is referring to sales not being successful. Otherwise I am confident by the advice you have been given by locals in your area have no idea what they are doing. If they did they would have never sold you 30 volt panels for a 24 volt battery using PWM controller. That alone tells us they are ignorant.

As I stated before with any PWM controller Output Current = Input Current. You need to fully understand what that means. Your panels are rated 7.94 amps and with 4 in parallel a total current of 31.76 amps. So the maximum charge wattage on the battery is 31.76 amps x 24 volts = 762 watts. Problem is your panel voltage is too low to push that much current.

With a MPPT controller Output Current = Panel Wattage / Battery Voltage. 1000 watts / 24 volts = 42 amps.

So if you want your system to work, use the right equipment and hardware. As state din my first post there is nothing wrong with the equipment. All of your problems are Operator Error in design and implementation.

Yes It could be the case as MPPT are Exhorbiantly expensive. And because they don't sell well, People who import them are able to charge exploitative premium on them. Solar stuff is already too expensive in India and there is zero help from Goverment makes it worse.

What shall be a better panel voltage to charge 24v system via PWM? If so I could ask him to change the type of panels. Otherswise,
If you are confident I will coax him into getting a 40A 24v MPPT controller. That'll do?

Thanks for detailed info.

[russ]

He is incompetent and you should not deal with that person. I take it you are in India? If so we cannot really help you are you do not have access to quality products.

Another problem he has is that in India the "electrical technician" is often the guy that has a screwdriver. If he has actually seen anyone do the job before he may have a vague idea.

[Sunking]

I see.
he was saying that if I buy a 40a mppt controller, it won't even start until panels give it 40a to work with. that's really fishy.

He is incompetent and you should not deal with that person. I take it you are in India? If so we cannot really help you are you do not have access to quality products.

[bhvm]

I see.
he was saying that if I buy a 40a mppt controller, it won't even start until panels give it 40a to work with. that's really fishy.

I'm going to push him for. mppt again. problem if I force him into something, I'll be left alone. if it doesn't work out, I'll have a huge dent in pocket and wasted hardware. hence I'm looking for maximum info. some of the members are not well versed wish Indian conditions and psychology I see. thanks for info.